The present invention relates to mechanical face seals.
It is known to design mechanical face seals to take account of distortion of the seal face members due to the pressure differential which will be applied across them during service. Such pressure distortion controlled seals are covered by British Patent No. 1 555 765. However, these seal face members are subject to significant temperature gradients due to heat generation at their interface and the resulting thermal distortion may be greater than pressure distortion, causing the sealing faces to rotate out of the plane in which they should be to provide acceptable sealing conditions. With conventional mechanical face seals deformation of the seal face members will cause the sealing faces of both seal face members to rotate towards the service that is the sealed fluid. Misalignment of the sealing faces is consequently the sum of rotation of the two sealing faces.
In this specification "rotation" signifies deformation of the sealing face out of the plane, usually perpendicular to the axis of rotation, in which the sealing faces are designed to engage when not subjected to temperature gradients. Positive rotations denote deformation towards the service and negative rotations denote deformations away from the service.